The present invention relates to a mechanism for discharging debris produced when a workpiece such as semiconductor wafers, various hard disks, glass substrates, liquid crystal panels, etc. is polished, and a polishing apparatus.
A conventional CMP (Chemical Mechanical Polishing) apparatus for use in the process of fabricating semiconductor integrated circuit devices comprises a polishing cloth mounted on a turntable and a rotatable top ring for holding a substrate to be polished against the polishing cloth to polish a surface of the substrate (free abrasive polishing) while a polishing slurry is being supplied to the polishing cloth. However, the conventional CMP apparatus is problematic in that it may fail to sufficiently planarize a surface to be polished depending on the type of pattern on the surface or the state of steps (surface irregularities) on the surface.
There has been developed a bonded-abrasive polishing process, which is to be used instead of the CMP apparatus of the above structure. In the process, a substrate to be polished is pressed against a bonded-abrasive and the substrate and the bonded-abrasive are slid relatively to each other while an abrasive liquid (solution) is supplied to the surface of the bonded-abrasive, thereby polishing the substrate.
When the substrate is polished using the bonded-abrasive, however, debris produced by the polishing process, such as waste bits produced by the polishing process, large grain fragments separated from the bonded-abrasive when the bonded-abrasive is dressed, or diamond particles released from the dresser, remains on the surface of the bonded-abrasive, tending to make scratches (flaws) on the surface of the substrate to be polished. Almost no effective means for discharging such debris produced by the bonded-abrasive polishing process has yet been available.
The present invention has been made in view of the above drawbacks. In particular, it is an object of the present invention to provide a mechanism for effectively discharging debris produced when a substrate is polished by a bonded-abrasive, and a polishing apparatus.
To achieve the above object, there is provided in accordance with the present invention a polishing apparatus for pressing a surface to be polished of a substrate against a bonded-abrasive surface and for moving the surface to be polished and the bonded-abrasive surface relative to each other to polish the surface to be polished. A mechanism is provided for discharging debris produced on the bonded-abrasive surface when the surface to be polished is polished.
With the above arrangement, debris produced when the substrate is polished, large grain fragments separated from the bonded-abrasive surface when the bonded-abrasive surface is dressed, or diamond particles released from a dresser used to dress the bonded-abrasive surface, can effectively be removed from the bonded-abrasive surface and the surface to be polished of the substrate. Thus, scratches (flaws) are effectively prevented from being made on the surface of the substrate being polished.
Preferably, the mechanism for discharging debris may comprise a debris discharging component for discharging the debris. The debris discharging component may comprise grooves defined in the bonded-abrasive surface for discharging the debris therethrough, and a fluid ejecting component for ejecting a liquid or gas in and along the grooves to discharge the debris out through the grooves. In a scroll-type polishing apparatus which incorporates the above mechanism, a liquid such as water, a chemical liquid, or the like can be supplied to a polishing surface provided by the bonded-abrasive surface from below the polishing surface to lubricate and cool the polishing surface and also to discharge the debris effectively out through the grooves. In a table-type polishing apparatus with a bonded-abrasive plate incorporating the above mechanism, debris can also be effectively discharged from a bonded-abrasive surface.
FIG. 1A is a fragmentary schematic side elevational view of a polishing apparatus according to a first embodiment of the present invention, and FIGS. 1B and 1C are a fragmentary schematic plan view and a perspective view, respectively, showing the positional relationship of a bonded-abrasive and a trapping jig;
FIG. 2 is a view showing a modification of the structure shown in FIG. 1C;
FIG. 3 is a view showing another modification of the structure shown in FIG. 1B;
FIGS. 4A and 4B are views showing still another modification of the structure shown in FIG. 1C;
FIGS. 5A through 5C are views of a polishing apparatus according to a second embodiment of the present invention, FIG. 5A being a fragmentary schematic side elevational view of the polishing apparatus, FIG. 5B a fragmentary schematic plan view of the polishing apparatus, and FIG. 5C a fragmentary schematic plan view of a modification of the polishing apparatus;
FIGS. 6A through 6C are views of a polishing apparatus according to a third embodiment of the present invention, FIG. 6A being a fragmentary schematic side elevational view of the polishing apparatus, FIG. 6B a fragmentary schematic plan view of the polishing apparatus, and FIG. 6C a fragmentary schematic plan view of a modification of the polishing apparatus;
FIGS. 7A and 7B are views showing a bonded-abrasive 70 used in a polishing apparatus according to a fourth embodiment of the present invention, FIG. 7A being a plan view of the bonded-abrasive, and FIG. 7B a sectional side elevational view thereof, i.e., a cross-sectional view taken along line Bxe2x80x94B of FIG. 7A;
FIGS. 8A, 8B, and 8C are views showing respective modifications of the bonded-abrasive;
FIGS. 9A through 9C are views showing a bonded-abrasive 80 according to a modification, FIG. 9A being a plan view of the bonded-abrasive, FIG. 9B an enlarged view of a groove 81 of the bonded-abrasive, illustrating the manner in which the bonded-abrasive operates, and FIG. 9C a view of the groove shown in FIG. 9B, taken along a line perpendicular to the plane of the view shown in FIG. 9B, illustrating the manner in which the bonded-abrasive operates;
FIGS. 10A through 10C are views showing a bonded-abrasive 90 according to another modification, FIG. 10A being a plan view of the bonded-abrasive, FIG. 10B an enlarged view of a groove 81 of the bonded-abrasive, illustrating the manner in which the bonded-abrasive operates, and FIG. 10C a view of the groove shown in FIG. 10B, taken along a line perpendicular to the plane of the view shown in FIG. 10B, illustrating the manner in which the bonded-abrasive operates;
FIG. 11 is a vertical cross-sectional view of a scroll-type polishing apparatus;
FIGS. 12A and 12B are views showing a scrolling motion, FIG. 12A being a plan view and FIG. 12B a cross-sectional view taken along line Axe2x80x94A of FIG. 12A;
FIGS. 13A through 13C are views showing the structure of grooves according to a fifth embodiment of the present invention, FIGS. 13A and 13B being cross-sectional views, and FIG. 13C a plan view;
FIGS. 14A through 14C are views showing sloping barriers, FIG. 14A being a cross-sectional view of the sloping barriers, FIG. 14B a plan view of the sloping barriers, and FIG. 14C a plan view showing the structure of sloping barriers with a discharge passage defined centrally therein; and
FIGS. 15A and 15B are views showing an automatically vertically movable barrier according to a modification, FIG. 15A being a cross-sectional view of the automatically vertically movable barrier when it is in use, and FIG. 15B a cross-sectional view of the automatically vertically movable barrier when it is not in use.